Collapsible dispensing containers have been widely used for packaging various preparations. Metallic tubes were used in the past for packaging pharmaceutical products, cosmetics, toiletries and other preparations which contain volatile ingredients since metals are impervious to oxygen, moisture and such volatile ingredients. However, metal tubes are costly to produce due to high costs of the metals (usually aluminum or lead) used in making the tubes, and the manner in which the tubes must be made.
Plastic tubes have also been widely used in the past for packaging cosmetics and personal preparations such as shampoos, etc. While plastic tubes are less costly to produce than metal tubes, and they are generally relatively inert to most chemicals, they are usually a poor barrier to moisture, oxygen and volatile ingredients such as essential oils, perfumes, mustard, dentifrices, medicinal ointments, shaving creams, etc.
Attempts have heretofore been made to extend the use of plastic tubes for packaging preparations which contain volatile ingredients by using a laminate structure which comprises a barrier layer of a metal foil (e.g., aluminum) laminated to a plastic (e.g., polyethylene). Tubes having such laminated wall construction combine the desirable properties of both plastics and metals and have found widespread commercial acceptance. One example of such tube is described in U.S. Pat. No. 3,260,410, issued to Roger Brandt and Ralph Kaercher on July 12, 1966 which is owned by the assignee of this present application. The laminated structure used in making the tubular body of the collapsible dispensing container described in the aforementioned patent comprises a metal foil barrier layer and a layer of a copolymer of olefin (e.g., ethylene) and a polar group-containing monomer (e.g., acrylic acid), with the preferred copolymer being ethylene-acrylic acid copolymer.
A further advance in the collapsible dispensing container art is represented by U.S. Pat. No. 3,347,419 issued to Roger Brandt and Nicholas Mestanas on Oct. 17, 1967 which is also assigned to the assignee of the present application. The tubular body of the collapsible tube described in the latter patent is made of a laminated sheet comprising an intermediate metal foil layer (e.g., aluminum) and an inner layer of a thermoplastic polymer (e.g., polyethylene) which is adhesively bonded to the foil layer by means of a copolymer of olefin (e.g., ethylene) and a polar group-containing monomer (e.g., acrylic acid). Again, and as in the aforementioned U.S. Pat. No. 3,264,410, a copolymer of olefin and acrylic acid constitutes the preferred adhesive copolymer. The thermoplastic inner layer affords improved bonding between the tubular body and the headpiece of the container, which itself is usually made of polyethylene.
Other patents of interest in the collapsible dispensing container art, and the laminate structures used in their construction, are represented by U.S. Pat. Nos. 3,172,571 issued on Mar. 9, 1965 to Nicholas Marchak; 3,295,725, issued on Jan. 3, 1967 to Roger Brandt, and 3,505,143, issued to David Haas and Kurt Roesch on Apr. 7, 1970, all of which are also assigned to the assignee of the present application.
While the laminated structures heretofore employed in making the tubular bodies of collapsible dispensing containers effectively prevent product migration through the tube and are excellent against attacks by oxygen, moisture, essential oils and other volatile components of the contained products, they have not shown the requisite resistance to attacks by certain other hard-to-hold ingredients of various preparations. Thus, when preparations which contain acetic acid are packaged in such containers, the acetic acid migrates toward the foil interface and causes delamination of the foil.
It is accordingly an object of this invention to provide a collapsible dispensing container which is uniquely suitable for packaging such hard-to-hold products.
It is also an object of this invention to provide an improved laminated structure for making the tubular bodies of such collapsible dispensing containers.
It is a further object of this invention to provide a laminate structure characterized by improved stress crack resistance, improved impact strength, improved resistance to delamination and imperviousness to acetic acid and preparations which contain acetic acid.
The foregoing and other advantages of this invention will become more apparent from the following detailed description of its preferred embodiment and the accompanying drawings.